The direct growth of carbon nanotubes as vertical interconnects in 3D integrated circuits

Carbon nanotubes (CNT) have been proposed for many applications in integrated circuits (IC): ranging from transistors and interconnects to sensors and actuators. For these applications it is crucial to integrate CNT directly alongside electronics, something which has not been achieved before. In this work we demonstrate the direct growth of CNT alongside CMOS devices, by integrating CNT as vertical interconnect (vias) in a monolithic 3D IC process using techniques and materials compatible with semiconductor technology. The electrical performance of both the CNT vias and the electrical devices is investigated and compared with the literature. From this we can conclude that the CNT growth has no significant impact on the electrical devices, although the resistance of the CNT should be further reduced to compete with metal interconnects. This demonstrates the viability of integrating CNT with IC, which is an important step forward in the application of CNT in electronics.